Case Study Question 1 on Solutions – Chapter 2 CBSE Class 12 Chemistry
Read the given passages and answer the questions that follow:
The spontaneous flow of the solvent through a semipermeable membrane from a pure solvent to a solution or from a dilute solution to a concentrated solution is called osmosis. The phenomenon of osmosis can be demonstrated by taking two eggs of the same size. In an egg, the membrane below the shell and around the egg material is semi- permeable. The outer hard shell can be removed by putting the egg in dilute hydrochloric acid. After removing the hard shell, one egg is placed in distilled water and the other in a saturated salt solution. After some time, the egg placed in distilled water swells-up while the egg placed in salt solution shrinks.
The external pressure applied to stop the osmosis is termed as osmotic pressure (a Colligative property). Reverse osmosis takes place when the applied external pressure becomes larger than the osmotic pressure.
1. What do you expect to happen when red blood corpuscles (RBC’s) are placed in 0.5% NaCl solution?
Ans. RBC’s are isotonic with 0.9% NaCl solution, so they will swell and may even burst when placed in 0.5% NaCl solution.
2. Which one of the following will have higher osmotic pressure in 1 M KCl or 1 M urea solution?
Ans. 1 M KCl will have higher osmotic pressure because its dissociates to give K+ and Cl– ions while urea does not dissociate into ions in the solution.
3. Name one SPM which can be used in the process of reverse osmosis.
Ans. Cellulose acetate placed on a suitable support.
4. What are isotonic solutions?
Ans. Solutions having equal osmotic pressure are called isotonic solutions.
5. Write van’t Hoff equation for dilute solution.
Ans. pV = nRT,
Where, p = Osmotic pressure, n = Number of moles, V = Volume of solution in litre, R = Gas constant,
T = Temperature